Spark-plug



E. C. KAHN.

SPARK PLUG.

. APPLICATION FILED JUNE 24. 1919. j

Patehted Nov. 23, 1920.

EDWARD C. KAHN, MIL'WAUKEE, WISGOHSIN.

seamstress.

asaeeee.

Application filed June 24,

To all w 7mm it may-concern Be it known that I, EDWARD C. KAHN, a

citizen of the Unitedgtates, and resident of li'lilwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in Spark- Plugs; and I do hereby declare that the following is a full, clear, and exact description thereof.

My invention relates to new and useful improvements in spark plugs for the cylinders of internal combustion engines.

The salient diliiculty in insuring the provision of an adequate and reliable spark in the cylinder of an internal combustlon engine resides in the tendency of oil and carbon to accumulate on the electrodes, the oil forming an insulation against the free passage of the current, while the carbon consti-' tutes a ready cifwnductor tending to reduce or eliminate the spark gap, and the various conventional makes of spark plugs, while fairly reliable in operation when the engine cylinder is clean, become gradually coated with carbon at their sparking points and thus suffer a loss of efiiciency, particularly under the conditions of excessiveoil or carbon deposit which are oftentimes encountered.

It is therefore the object of my invention to provide a spark plug wherein the elec trodes are so arranged as to prevent interference with their sparking action by oil or carbon deposit, and it is more particularly my object to provide maximum coacting sparking expanses of the electrodes to insure opposed-active sparking surfaces at all times and to provide a maximum size of spark.

it is further my object to provide an arrangement wherein the sparking surfaces of the electrodes are shielded from a dripping action of oil 'or condensed fuel which may accumulate upon other portions thereof.

it is still further my object to increase the intensity and size of the spark by providing for the accumulation of electricity on a spherical electrode surface from which the spark may jump at any point in an annular line.

lVith the above and other objects and advantages in View, which will be apparent as the description proceeds, my invention resides in the novel features of construction, combination and arrangement of parts which will be hereinafter. more particularly Specification of Letters Patent.

Patented Nov. as, 1920. 1919. Serial no. soas'm.

described and defined by the appended claims.

In the accompanying drawings:

Figure 1 is a sideelevational view of a spark plug, with its lower portion in section to show my improved electrode structure.

Fig. 2 is a bottom view of the spark plug.

Referring now more particularly. to the accompanying drawings, 5 designates the ordinary metallic shell or casing of a spark plug, said shell being threaded for engagement with the cylinder of an internal combustion engine, and forming the ground connection for the plug. The usual insulating filler 6 is disposed within the shell, through which extends the usual insulated stem 7.

In the present embodiment of my inven' tion, the lower end of this stem is enlarged in inverted cup-shape to form a female electrode 8, which receivesin spaced relation to its inner surface, a spherical male electrode 9 carried by a rod 10 depending from the shell 5, said rod being bent inwardly and then upwardly to support the electrode 9 in proper position. The inner surface of the female electrode 8 is partly spherical in contour, the curvature of said surface being such with respect to the curvature of the spherical male electrode 9 that the radial distances between the surfaces are progressively increased toward the center of the fe-' male electrode and the edge or mouth portion of the cup of the female electrode is disposed at proper sparking distance from the adjacent surface of the male electrode, thus defining an annular spark gap. The diameter of the mouth of the female electrode is slightly greater than the diameter of the male electrode, and thus any oil or condensed fuel which may accumulate'on the female electrode will not drip upon the male electrode, which is thus shielded.

In the operation of my improved spark plug, as the spark impulse is transmitted to the positive electrode, the electricity will spread and accumulate on the spherical surface of said electrode and will then jump through that portion of the annular sparking space between the electrodes, which is in mostfavorable condition at the moment of sparking, and the spark in jumping will spread about the annular sparkin surface to procure an adequate expanse of t e spark. Efficient and reliable operation of the plug 2 1 ,seaeee is thus insured, particularly by reason or the provision of an annular sparking space wherein the most favorable portion may be utilized at each spark period for transmission of the spark, it being noted that due to the explosion condition in the engine cylinder, the condition of the electrode face portions defining the sparking space would vary, but at least one portion would be in proper condition to transmit the spark.

\Vhile l have shown a preferred embodiment of my invention as comprising a male spherical electrode engaged in a cup-shaped female electrode, it Will be appreciated that an important feature of my invention resides in the provision of spaced opposed annular electrode surfaces, and the structure' may be varied Within the scope of the appended claims, to meet differing conditions of use and manufacture without departing in any manner from the spirit of the invention.

What is claimed is:

1; A spark plug including a cup-shaped female electrode member, and a male elec- 2. A spark plug including a casing, an in sulated stem extending through the casing,

an inverted cup-shaped electrode carried by said stein, and a spherical electrode carried by the casing below the cup-shaped electrode with its upper portion extending into the cup-shaped electrode and spaced therefrom to define an annular spark gap, the diameter of the mouth of the cup-shaped electrode being greater than the diameter of the spherical electrode.

In testimony that I claim the foregoing I have hereunto set my hand at Milwaukee,

in the county of Milwaukee and State of Wisconsin.

EDWARD O. KAHN. I 

